On Thursday, a trailer-truck carrying an oversize load clipped a steel truss, starting the collapse of the span and sending cars and people into the cold river waters, authorities said. The three people in the cars survived with non-life threatening injuries.

But the collapse cut access to one of the most important highways in Washington state for trade, commuters, and travelers.

Debbie Hersman, National Transportation Safety Board chairwoman, on Sunday said the bridge had withstood similar incidents, with the most recent reported last October. She said evidence of other collisions can be seen in the spans still standing over the water.

Hersman also said a second truck with a similar cargo was traveling behind the truck involved in the incident. She said investigators are inspecting that cargo and truck to take measurements. The truck that hit the truss has been moved off the highway on-ramp, where it had been parked since Thursday.